62 MARVELS OF PO>'D-LIFE. 



transferred with a very small drop of water to the 

 live box. Then the cover had to be put on so as 

 to squeeze the animal just enough to keep it still 

 without doing it any damage, or completely stopping 

 its motions. This was a troublesome task, and 

 often a little over-pressure prevented its success. 



Some observers always use in these cases an in- 

 strument called a compressorium^ by which the 

 amount cf pressure is regulated by a lever or a fine 

 screw; but whether the student posseses one or not, 



Pterodina patina— tail-fcot. 



he should learn to accomplish the same result by 

 dexterously manipulating a well-made live box. We 

 will suppose the Pterodina successfully caged, and a 

 power of about one hundred and fifty linear brought 

 to bear upon her, for our specimen is of the ^'female 

 persuasion." This will suffice to demonstrate the 

 disposition and relation of the several parts, after 

 which one of from four hundred to five hundred linear 

 may be used with great advantage, though in this 

 case the illumination must be carefully adjusted, and 



